Locking device



' Aug. 8,1950 w. F. KLEMM 2,518,334

LOCKING DEVICE Filed sept. s, 1945 2 sheets-sheet 1 INVENToR. M/zZZ'd/nFila/707e.

Aug. s, 195o w. F. KLEMM 2,518,334

` LOCKING DEVICE Filed sept. s, 1946 n 2 sheets-sheet 2 BY /40/ .E

Patented ug. 8, 12950 UNITED vS".l`ATl-SVV PATENT.V OFF'C LOCKING DEVICEj Wimamr. .Klemm, Detroit, Mien. Y Application September 3, 1946;Serifal'No; 694,651

(icl. 19a- 8) 8 Cla-ims.

This invention relates to clamping fixtures, and more `particularlytoxclamping iixturesl adapte yed to clamp an` .object with apredetermined clamping force and to lock therfmture .against release.v i

The'main objects of the present invention are: toprovidean improvedclamping iixtnre adapted to` clamp an object with a predetermined,clamp- "ing force 'and'. then lock in Lposition to prevent damage touorrelease of theA` objectclarnped; to provide an improved vclarrniingxture of rthe above generally indicated type which is simple inconstruction, economical of `manufacture and assembly, andi reliable andeihoient in operation; towp'rovide aclamping iixture' withimproved:means for readily adjusting the fixture to lock in position upon theapplication of any desired predetermined yclamping force` uponanlo'bjectto be clamped; and to generally improve the construction andoperation of clamping xtures of the above generally indicated'type.

Otherobje'ctsand features of: novelty .of the invention will be.specifically pointed: out-or will ibecomeapparent Vwhen referring, tora better understanding foi the invention', to the following Idescriptiontaken in conjunction -wf'ith theaccompanying. drawings, wherein:

.Figure l is a plan. viewshowing. partsA in `section,l of aclampingfixturexembodying features of this invent-ion;

IFig. 2. is" afsectional view `of. the: structurey illus trated inflig.41,. taken .substantially along' the linev 2*-2 thereof;

Fig. 2?` isv asectilonal View or a clamping fixture, similar tothatillustrated inA Fig. l, showing a further form which the invention mayassume; .w Fig. 4L is. a sectional view' .ot structure, similar to thatillustrated in;- Fig.1 la/showing a further form-1 whichrtheinventionmayassume;l

5t-is asecti'onal View of another form. or .clamping fixture i, whichembodies features: or? :the

' Vpresent'nvention;

fis" integrally formed thereon for slidably supporting twoV verticallydisposed parallel columns t8 anda horizontally disposed shaft 2l). Eachof the columns i3 has a vertically' disposed rack 22 formed along oneside thereof, and the shaft 2|] has an elongated spur gear 24`integrally formed thereon which continuouslymeshes with the racks 22 formoving thecolumns I`8 verti lcally in the housing Iii when rotated. AtVtheir upper ends; yeach of the columns I8 is' provided with an upwardlyprojecting stud` 26 -which extends through the plate 28 and receives anut 3B. The pla-tcl8 seryesas- ,a second clamping jaw and cooperateswith the dat portion :I4 of the base I2 to clamp an object therebetween.

One end of theshaft 2li has a head 232 integrally formed thereon adaptedto engage the housing I6. inV which the shaft is rotatably supported.Adjacent tofits' other end, the shaft has a threaded portion 34 whichextends outwardly of said housing.r A handle .36 is threaded onsaidportion 34 and has a cylindrical bore 381' formed in its :outer end.One end oi a compression coil spring .40 is received in said bore forengagement with .said handle and the other end is received in a recess-of a nut 42 threaded on the outer end of the shaft 20. The' nut d2 maybe adiusted on the shaft 2i), to produce any `desired compression in thespring 40 and may be securely held in that ,position by kan Alllenheadset screw 44 or like means. A

In the construction above described, when an objectto be clamped isplaced between the jaws 'I4 and 28- and the handle 36 isl rotated ina'ycounterclockwise direction as viewed from the right in Fig. 1, theshaft 2B is' caused to turn with the vhandle as a resultV ofthe'frictional engagement between the threads on the handle 36 and thethreads on the shaft 20; The amount of this frictional force may bevaried by adjusting the nut 42 to alter the compression of the spring40, as above described. This rotation of the handle 36 and the shaft 20drives the column I8 vertically downward, as viewed in Fig. 2, throughthe engagement of the spurgear ,24:and the racks 22. The jaw 28 is movedtoward the jaw I4- in this manner until a predetermined amount ofgripping force is .applied to the4 object held therebetween, at whichtime the handle 3S begins to turn relative to the shaft 20 to beadvanced on the threaded portion 34 .of the shaft toward the head 32until the head 32 and the handle 36 grip-opposite sides of the ,housinglr6 and thereby prevent further rotation of the handle. This produces awedging action between the threads on the handle 36 and those on theshaft 20, and a pressure between handle 36 and the housing I6 whichcombine to lock the handle 36 in position against inadvertent movementin a clockwise or releasing direction. Further movement of the handle 36in a clamping or counterclockwise direction is positively prevented bythis locking engagement.

When desired the clamp may be easily released by rotating the handle ina clockwise direction. This causes the handle 3E to advance along theshaft 20 until the housing I6 is no longer gripped between the head 32and the handle 38, after which the shaft 20 turns with the handle 30 asa result of the frictional force developed between the handle 35 and theshaft by the spring lllV a described above. l

It will be apparent that if right-hand threads `instead of the left-handthreads illustrated are employed on the shaft 20, the clamping actionwill be effected by rotating the handle in the opposite direction. Thedirection of movement of. the clamping jaws for a given movement of thehandle may also be reversed by disposing the shaft and associated gearon the opposite side of the .columns from that shown.

In the modified form of the invention illustrated in Fig. 3, the shaft50, corresponding to the shaft 20, extends between'the verticallydisposed columns 52, corresponding to the columns I8, and the gear 54carried by the shaft 50 engages a rack formed on one of the columns 52.The handle S, corresponding to the handle 36,

'has a blind bore 58, the outer portion of which is threaded. This formof the invention is particularly adapted for clamping fixtures in whicha relatively light clamping force is desired, and accordingly a smalland relatively weak compression coil spring 60 is disposed within theinner portion of the bore'58. One end-of the spring 60 engages thehandle at the inner end of the bore 58 and the other end of the spring6G engages the outer end of the shaft 50 upon which the h andle 58 isthreaded. 'The spring 60 functions to produce a-frictional engagementbetween the handle 58 and the shaft y5E) corresponding to but-muchsmaller'than the frictional engagement between the handle 36 and theshaft 2D in the embodiment described above.

In the `modification illustrated in Fig 4, the handle 62 differs fromthat of the construction shown in Fig. 3, in that the blindbore formedtherein has an internal portion S which is threaded for engagement withthe threaded end of the shaft |36 and an outer portion 68 which isenlarged to receive a coil spring l0. Y The spring surrounds the shaft65 and one end thereof engages the gear 'I2 and the other end engagesthe handle 52 at the inner end of the outer enlarged portion '68 of thebore. This larger spring 10 permits a greater clamping force than thespring 60 while bothY features are designed for a set load that can onlybe changed by changing the springs. Another formof the invention isillustrated in Fig. 5, that wherein a fixture employs a shaft 80 havinga tapered head 82 corresponding to the head 32 and a gear S4 engaging arack 8E formed on a single column 88. The portion of the shaft 8Gextending outwardly of the handle Si?, which is threaded thereon, has anaxially extending groove formed therein which receives a complementarytongue. formed on an inner spring sup- Cil port member S6. The member 86is slidable axially of the shaft and has a conically shaped surface 98on the inner side thereof adapted to engage a complementary conical seat|00 formed on the handle 9G. A nut |e2, similar to the nut 42, isthreaded on the outer end of the shaft 80 and a compression coil spring|04 is supported between the inner spring supporting member 95 and thenut |02.

. It will be appreciated thatthe clamping fixture of Fig. '5. permits asubstantially greater clamp- Ving force to be applied'to the objectbeing clamped than is possible with the clamping fixtures -so fardescribed. This results from the additional frictional force which isset up between the conical surface 98 of the inner spring member 96 andtheA conical seat |00 formed in the handle which must be overcome inaddition to the frictional force of the threaded engagement between thehandle 90 and the shaft 8e before the handle may turn relative to theshaft and advance along the shaft to grip the 'housing |05 between thehead 82 on the shaft and the handle 90.

These frictional forces effective to cause the handle 90 and the shaft80 to turn as a unit may be variedin this construction as in theembodiment illustrated in Figs. 1 and`2, by adjusting the outer springsupport |02 along the shaft 80 to vary the pressure of the spring |04.

The form of the invention illustrated in Fig. 6 differs from theconstruction 4shown in Figs. l and 2 in that a torsional spring ||0` isemployed, havingits inner end anchored in the handle I|2 and its outerend anchored'in a nut I4 threaded -on Ythe outer'end of the shaft H6.'The spring ||0 is arranged to apply a torque to the nut H4, .tending tothread the nut outwardly on the shaft H6 and the nut I I4 'is heldagainst movement in that direction by a second nut ||8 threaded on theouter end of .the shaft I6.

In this construction,A when the handle ||2 is rotated in a clampingdirection or in a' counterclockwise direction,V as viewed from` theright in Fig. 6, the torque action of the spring IIB, resisting furtherwinding up of the spring, causes the shaft ||6 to turn with the handleuntil the clamping force applied is such that the force required 'tovturn the handle I I2 is greater than the torque action of the spring||0,.at which time a handle ||2 turns relative tothe shaft III. YThespring I'IIJ thereafter is further wound up until the handle I I2 andthe opposite end of the shaft grip the housing ||9 and preventgfurthermovement of the handle as in the above described structures.

Fig. 7 illustrates analternative means which may be mounted on the endof the shaft opposite to that which receives the handle and whichreplaces the heads 32 and 82 integrally formed on the shafts in theconstructions Yillustrated in Figs. l and 5, respectively. Thisalternative means comprises a nut |20 threaded on an outwardly extendingYportion of the shaft |22 and secured against rotation relative theretoby a cotter pin |24. The nut |20 grips the housing |26 i 'the samemanneras does the head 32 and may be removed to permit the shaft |22 to beinserted from either side of the housing |26.

Fig. 8 illustrates a modified formof thread construction whichmay beemployed in any of the above described clamping fixture constructions'tomaterially increase the clamping force which may be appliedthereby. Inthis construction the threadsfare formed with .a substantially :atraenincreased 'thread angie.. said :angie being that betweenadiaoentfthreadffaces '13u andl'sz. The deptnof theithreadis reduced byproviding hats $134 at the bottom of vthe threadsrand similar flats .136`at thewapex.' This construction provides `a 'substantially'increasedfwedgingxaction between "the fthreaded velements' .and therefore asubstantiallysgreater -frictional force therebe- =betweenyvliich:inustbeovercome before one element may turn relative totherother.

(As illustrated `in .9, the invention is readily applicable to clampingxtures having a C-shaped base |40, the-upper arm 'M2 of which carriesone clamping jaw i443 In thisconstruction the plate 6, mounted on thecolumn |748 corresponding-to the column I8, serves as the lower clampingjaw and the movementY ofthe Icolumnv l''in a clampingdirection isupwardly,.asf opposed to the conco-pending application, Serial No.573,432, filed January 18, 1945. Assurance is had that the specimensexamined are clamped with a like pressure and that no damage resultsthereto from the clamping operation.

What is claimed is:

l. In a clamping xture, a pair of relatively movable elements employedfor clamping an object therebetween, a rack mounted on one of saidelements, gear means adapted to engage said rack vmounted on the otherof said elements, a shaft operatively connected to said gear means andhaving a threaded portion on one end thereof, a handle having a threadedengagement with said threaded portion, means biasing said handle axiallyof said shaft, and gripping means operable upon the application of apredetermined clamping force upon said object by said elements to gripone of said elements and lock said handle against further movement in aclamping direction.

2. In a clamping xture, a pair of relatively movable elements employedfor clamping an object therebetween, a rack mounted on one of saidelements, gear means adapted to engage said rack mounted on the other ofsaid elements, a shaft operatively connected to said gear means andhaving a threaded portion on one end thereof, a handle having a threadedengagement with said threaded portion, adjustable means for variablybiasing said handle axially of said shaft, and gripping means operableupon the application of a predetermined clamping force on said object bysaid elements to grip one of said elements and lock said handle againstfurther movement in a clamping direction.

3. In a clamping fixture, a pair of relatively movable elements employedfor clamping an object therebetween, a rack mounted on one of saidelements, gear means adapted to engage said rack mounted on the other ofsaid elements, a shaft operatively connected to said gear means and haing a threaded portion on one end thereof, a ha le having a threadedengagement with said 4threaded portion, means including a coil springbiasing said handle axially of said shaft, and gripping means operableupon the application of a predetermined clamping force upon said objectsby said elements to grip one of said elements and lock said handleagainst inadvertent movement.

f1, In a clamping xture, a pair of relatively .movable elementsemployedfor clamping arrobject therebetween, a rackk mounted ont` oneofsaid elements,` gearr means adapted to engage said rack mounted ontheother of said elements, ya shaft .operatively connected to said gearrmeans and having a threaded portion on one endthereof,1a handlev havinga threaded engagement with "saidthreaded portion, a spring supportmounted on'said one end of said shaft, a compression vspring vengaging:said .spring support .and said handle to bias said handle axially ofsaid shaft, and grippingmeans operable upon'the application ofapredetermined clamping force upon said object by said elements to` gripone of said elements and locksaid handle against inadvertent movement. vf

5.V In Va clamping fixture, a pair of relatively movableelementsemployed yfor clamping anob- Aject therebetween,v a rack mountedon one of said elements, Vgear `means adapted to engage said racklmounted on .the other of said elements, a

vshaftoperatively connected to said ,gearg means Aand having athreadedportion on one end'thereof, a handle having a threadedengagement with said threaded portion, a spring support mounted on saidone end of said shaft, a compression spring engaging said spring supportand said handle to bias said handle axially of said shaft, and grippingmeans operable upon the application of a predetermined clamping forceupon said object by said elements to grip one of said elements and locksaid handle against inadvertent movement, said gripping means includinga head formed on the other end of said shaft from said thread and anintegral portion on said handle having a surface adapted to abut theopposite side of said one of said elements from the head to clamp saidlast element therebetween.

6. In a clamping fixture, a pair of relatively movable elements employedfor clamping an object therebetween, a rack mounted on one of saidelements, gear means adapted to engage said rack mounted on the other ofsaid elements, a shaft operatively connected to the gear means andhaving a threaded portion on one end thereof, a handle received on saidthreaded portion and having a threaded engagement therewith, a springsupport threaded on said one end, said spring support being adjustablealong said threaded portion and having a setscrew for securing saidspring support in an adjusted position, a coil spring engaging saidspring support and said handle to bias said handle axially of saidshaft, and gripping means operable upon the application of apredetermined clamping force upon said object by said elements to gripone of said elements and lock said handle against inadvertent movement.

7. In a clamping xture, a pair of relatively movable elements employedfor clamping an object therebetween, a rack mounted on one of saidelements, gear means adapted to engage said rack mounted on the other ofsaid elements, a shaft operatively connected to said gear means andhaving a tapered head on one end thereof and a threaded portion on theother end thereof, a handle having a threaded engagement with saidthreaded portion, means operatively connecting said handle to said shaftto cause said handle and said shaft to turn as a unit until said objectis clamped between said elements with a predetermined clamping force,gripping means operable when said object is clamped with saidpredetermined clamping force to grip one of said elements and lock saidhandle against inaclyer` fcal member.

8. In a clamping xture, a pair of relatively movable elements employedfor clamping an ob- `'ject therebetween, a rack mounted on one of saidelements, a gear means adapted to engage said rack mounted on the otherof said elements, a

`shaft operatively connected to Said gear means and having a threadedportion on one end there of, a handle mounted on said one end of saidshaft and having a, threaded engagement therewith, a spring supportmounted on said one end fof said shaft, means preventing rotation ofsaid spring support relative to said shaft in at least Number onedireetiomagtorsional spring having one end anchored inf said springsupport and the other Vend anchored in said vhandle and being eiectiveto' cause saidjhandle and said shaft to turn as a -unit until saidobject isv clamped between said elementslwith a predetermined clampingforce,

land gripping meansyoperableupon the application of said predeterminedclamping force to grip one .of said velements-and lock said handleagainst inadvertent movement,

, REFERENCES CITED Y The following references are' of record in the leof this; patent; 1

UNTTED STATES PATENTS Name s Date 1,457,745 Norris a. June 5, 19231,855,939 Collins Apr. 26, 1932 1,900,852 Kuppersmith Mar. 7, 1933 n2,339,708 Long, Jan. 18, 1944 Albrechtet al. Aug. 7, 1945

